/**
* Get a path from the local FS. If size is known, we go round-robin over the set of disks (via
* the configured dirs) and return the first complete path which has enough space.
*
* <p>If size is not known, use roulette selection -- pick directories with probability
* proportional to their available space.
*/
public synchronized Path getLocalPathForWrite(
String pathStr, long size, Configuration conf, boolean checkWrite) throws IOException {
confChanged(conf);
int numDirs = localDirsPath.length;
int numDirsSearched = 0;
// remove the leading slash from the path (to make sure that the uri
// resolution results in a valid path on the dir being checked)
if (pathStr.startsWith("/")) {
pathStr = pathStr.substring(1);
}
Path returnPath = null;
Path path = new Path(pathStr);
if (size == SIZE_UNKNOWN) { // do roulette selection: pick dir with probability
// proportional to available size
long[] availableOnDisk = new long[dirDF.length];
long totalAvailable = 0;
// build the "roulette wheel"
for (int i = 0; i < dirDF.length; ++i) {
availableOnDisk[i] = dirDF[i].getAvailable();
totalAvailable += availableOnDisk[i];
}
// Keep rolling the wheel till we get a valid path
Random r = new java.util.Random();
while (numDirsSearched < numDirs && returnPath == null) {
long randomPosition = Math.abs(r.nextLong()) % totalAvailable;
int dir = 0;
while (randomPosition > availableOnDisk[dir]) {
randomPosition -= availableOnDisk[dir];
dir++;
}
dirNumLastAccessed = dir;
returnPath = createPath(path, checkWrite);
if (returnPath == null) {
totalAvailable -= availableOnDisk[dir];
availableOnDisk[dir] = 0; // skip this disk
numDirsSearched++;
}
}
} else {
while (numDirsSearched < numDirs && returnPath == null) {
long capacity = dirDF[dirNumLastAccessed].getAvailable();
if (capacity > size) {
returnPath = createPath(path, checkWrite);
}
dirNumLastAccessed++;
dirNumLastAccessed = dirNumLastAccessed % numDirs;
numDirsSearched++;
}
}
if (returnPath != null) {
return returnPath;
}
// no path found
throw new DiskErrorException("Could not find any valid local " + "directory for " + pathStr);
}
/**
* Get the locally cached file or archive; it could either be previously cached (and valid) or
* copy it from the {@link FileSystem} now.
*
* @param cache the cache to be localized, this should be specified as new
* URI(hdfs://hostname:port/absolute_path_to_file#LINKNAME). If no schema or hostname:port is
* provided the file is assumed to be in the filesystem being used in the Configuration
* @param conf The Confguration file which contains the filesystem
* @param subDir The sub cache Dir where you want to localize the files/archives
* @param fileStatus The file status on the dfs.
* @param isArchive if the cache is an archive or a file. In case it is an archive with a .zip or
* .jar or .tar or .tgz or .tar.gz extension it will be unzipped/unjarred/untarred
* automatically and the directory where the archive is unzipped/unjarred/untarred is returned
* as the Path. In case of a file, the path to the file is returned
* @param confFileStamp this is the hdfs file modification timestamp to verify that the file to be
* cached hasn't changed since the job started
* @param fileLength this is the length of the cache file
* @param currentWorkDir this is the directory where you would want to create symlinks for the
* locally cached files/archives
* @param honorSymLinkConf if this is false, then the symlinks are not created even if conf says
* so (this is required for an optimization in task launches
* @param lDirAllocator LocalDirAllocator of the tracker
* @return the path to directory where the archives are unjarred in case of archives, the path to
* the file where the file is copied locally
* @throws IOException
*/
private static Path getLocalCache(
URI cache,
Configuration conf,
Path subDir,
FileStatus fileStatus,
boolean isArchive,
long confFileStamp,
long fileLength,
Path currentWorkDir,
boolean honorSymLinkConf,
MRAsyncDiskService asyncDiskService,
LocalDirAllocator lDirAllocator)
throws IOException {
String key = getKey(cache, conf, confFileStamp);
CacheStatus lcacheStatus;
Path localizedPath;
synchronized (cachedArchives) {
lcacheStatus = cachedArchives.get(key);
if (lcacheStatus == null) {
// was never localized
Path uniqueParentDir = new Path(subDir, String.valueOf(random.nextLong()));
String cachePath = new Path(uniqueParentDir, makeRelative(cache, conf)).toString();
Path localPath = lDirAllocator.getLocalPathForWrite(cachePath, fileLength, conf);
lcacheStatus =
new CacheStatus(
new Path(localPath.toString().replace(cachePath, "")), localPath, uniqueParentDir);
cachedArchives.put(key, lcacheStatus);
}
lcacheStatus.refcount++;
}
boolean initSuccessful = false;
try {
synchronized (lcacheStatus) {
if (!lcacheStatus.isInited()) {
localizedPath = localizeCache(conf, cache, confFileStamp, lcacheStatus, isArchive);
lcacheStatus.initComplete();
} else {
if (fileStatus != null) {
localizedPath =
checkCacheStatusValidity(
conf, cache, confFileStamp, lcacheStatus, fileStatus, isArchive);
} else {
// if fileStatus is null, then the md5 must be correct
// so there is no need to check for cache validity
localizedPath = lcacheStatus.localizedLoadPath;
}
}
createSymlink(conf, cache, lcacheStatus, isArchive, currentWorkDir, honorSymLinkConf);
}
// try deleting stuff if you can
long size = 0;
int numberSubDir = 0;
synchronized (lcacheStatus) {
synchronized (baseDirSize) {
Long get = baseDirSize.get(lcacheStatus.getBaseDir());
if (get != null) {
size = get.longValue();
} else {
LOG.warn("Cannot find size of baseDir: " + lcacheStatus.getBaseDir());
}
}
synchronized (baseDirNumberSubDir) {
Integer get = baseDirNumberSubDir.get(lcacheStatus.getBaseDir());
if (get != null) {
numberSubDir = get.intValue();
} else {
LOG.warn("Cannot find subdirectories limit of baseDir: " + lcacheStatus.getBaseDir());
}
}
}
// setting the cache size to a default of 10GB
long allowedSize = conf.getLong("local.cache.size", DEFAULT_CACHE_SIZE);
long allowedNumberSubDir =
conf.getLong("local.cache.numbersubdir", DEFAULT_CACHE_SUBDIR_LIMIT);
if (allowedSize < size || allowedNumberSubDir < numberSubDir) {
// try some cache deletions
LOG.debug(
"Start deleting released cache because"
+ " [size, allowedSize, numberSubDir, allowedNumberSubDir] ="
+ " ["
+ size
+ ", "
+ allowedSize
+ ", "
+ numberSubDir
+ ", "
+ allowedNumberSubDir
+ "]");
deleteCache(conf, asyncDiskService);
}
initSuccessful = true;
return localizedPath;
} finally {
if (!initSuccessful) {
synchronized (cachedArchives) {
lcacheStatus.refcount--;
}
}
}
}